This invention relates to a method of operating a working machine of the kind having a body, a ground engaging structure, and a working arm carrying a working implement.
It is known for operating functions such as the movement of a working arm of a working machine to be effected by hydraulic actuators which may be linearly acting actuators such as hydraulic rams, or rotationally acting actuators such as hydraulic motors, which are controlled by an operator using controls, usually from within a cab located in or on the body of the machine. It is also known for the operator controls to include proportional controls, so that a hydraulic actuator is operated to effect an operating function in correspondence with the direction and the magnitude of a control input to its operator control.
For example a working implement such as a boring tool may be carried by the working arm, and its operation i.e. speed of rotation of a boring bit, may be proportionally controlled by operating a rotational actuator of the tool in proportion to the direction and extent of movement of an operator control. When carrying out such a task, it can be advantageous for the rotational speed of the boring bit to be maintained at a certain level, but it can be difficult for an operator to control the boring tool rotational actuator for a sustained period to maintain the desired boring bit rotational speed, and/or the task may be interrupted, making it difficult for the operator to re-achieve the desired boring bit rotational speed.